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polynomial division fixes

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This commit is contained in:
Mirek Kratochvil 2012-05-14 00:03:35 +02:00
parent 022d20aa30
commit 2f8dfb56af
1 changed files with 20 additions and 18 deletions
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38
lib/polynomial.cpp
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@ -133,13 +133,9 @@ void polynomial::generate_random_irreducible (uint s, gf2m&fld, prng& rng)
{
resize (s + 1);
item (s) = 1; //degree s
item (0) = 1 + rng.random (fld.n - 1);
for (uint i = 1; i < s; ++i) item (i) = rng.random (fld.n);
while (!is_irreducible (fld) ) {
uint pos = rng.random (s);
item (pos) = pos == 0 ?
(1 + rng.random (fld.n - 1) ) : rng.random (fld.n);
}
for (uint i = 0; i < s; ++i) item (i) = rng.random (fld.n);
while (!is_irreducible (fld) )
item (rng.random (s) ) = rng.random (fld.n);
}
bool polynomial::compute_square_root_matrix (vector<polynomial>&r, gf2m&fld)
@ -300,7 +296,7 @@ void polynomial::sqrt (vector<polynomial>& sqInv, gf2m&fld)
void polynomial::div (polynomial&p, polynomial&m, gf2m&fld)
{
polynomial r0, r1, s0, s1, s2, q1, q2;
polynomial r0, r1, s0, s1, s2, q0, q1;
r0 = m;
r1 = p;
@ -308,25 +304,30 @@ void polynomial::div (polynomial&p, polynomial&m, gf2m&fld)
s0.clear();
s1 = *this;
s1.swap(*this);
s1.mod (m, fld);
while (r1.degree() >= 0) {
r0.divmod (r1, q1, q2, fld);
r0.divmod (r1, q0, q1, fld);
r0.swap (r1);
r1.swap (q2);
r1.swap (q1);
s2 = s0;
q1.mult (s1, fld);
q1.mod (m, fld);
s2.add (q1, fld);
q0.mult (s1, fld);
q0.mod (m, fld);
s2.add (q0, fld);
s0.swap (s1);
s1.swap (s2);
}
*this = s0;
make_monic(fld);
this->swap(s0);
//scalar divide by r0 head
if(r0.degree()<0) return;
uint c=r0[r0.degree()];
c=fld.inv(c);
for(uint i=0;i<size();++i) item(i) = fld.mult(item(i),c);
}
void polynomial::divmod (polynomial&d, polynomial&res, polynomial&rem, gf2m&fld)
@ -345,6 +346,7 @@ void polynomial::divmod (polynomial&d, polynomial&res, polynomial&rem, gf2m&fld)
for (uint i = 0; i <= degd; ++i)
rem[i+rp] = fld.add (rem[i+rp], fld.mult (res[rp], d[i]) );
}
rem.strip();
}
void polynomial::inv (polynomial&m, gf2m&fld)
@ -380,6 +382,6 @@ void polynomial::mod_to_fracton (polynomial&a, polynomial&b,
b0.swap (b1);
b1.swap (q);
}
a = a1;
b = b1;
a.swap (a1);
b.swap (b1);
}